People spend one third of their life times sleeping in the dreams, and sleeping is the most usual way for the human body to have a rest. For this reason, people are always trying their best to find a way to make themselves sleep more comfortable, so a variety of pillows are available in the marketplaces. However, some pillows have such a weak supporting force that the pillow caves in as soon as the user's head puts on the pillow, and the user's head feels like not being supported on it; some pillows have such a strong supporting force that the pillow user feels neck-stiff and cannot turn his neck around when he wakes up due to too strong spring-back force exerted on his neck by the pillow.
The suitable height of pillow is such that, the neck, the cervical vertebra and the backbone of the user are aligned with his head when sleeping on the pillow. When the pillow user lies on his back, he needs a pillow height different from that needed when he lies on his side. A nice pillow is such a pillow, the height of which can be suitably adjusted, so as to accommodate different sleeping postures.
Some different types of pillows are disclosed in the related items in Chinese Utility Model patent (Publication Number) CN 2524605, 2671613, 2162865, 2501409 and 2482913. However, none of these types of pillow is able to solve the above-described problem, that is, the height of the pillow is capable of self-adjusting to meet the requirements of different sleeping postures while not exerting any spring-back pressure.